Apparatus for voltolization



Feb. 23, 1937.

L. MATHESON APPARATUS FOR VOLTOLIZATION Filed Aug. 25, 1935 3 Sheets-Sheet 1 G. L. MATHESON 2,071,551

APPARATUS FOR VOLTCLIZATION Filed Aug. 25, 1955 s Sheets-Sheet 2 Feb. 23, 1937.

Patented Feh. 23, 1937 PATENT OFFICE 2,071,551 APPARATUS FOR vouromza'rron George L. Matheson, Union, N. J., assignor to Standard Oil Development Company, a corporation of Delaware Application August 23, 1935, Serial No. 37,450 6 Claims. (01. 204-31) This invention relates to improvements in apparatus for treating materials with silent electric discharges. This treatment is often called voltolization, and consists essentially in passing an alternating current of high frequency through gas in contact with a thin film of oil or other material while maintained under vacuum.

One type of apparatus used for voltolization is the trommel type. This comprises a drum provided with a rotatable shaft therein on which are disposed a plurality of electrodes separated each from the other by insulators. Alternate electrodes are connected to opposite poles of the source of alternating current so that the discharge occurs between each pair of electrodes. The shaft with attached electrodes is adapted to be rotated Within the drum. Oil or othermaterial to be treated is introduced into the bottom of the drum. As the electrodes on the shaft rotate they pick up oil from the bottom and as they rotate farther this oil drips down over the surface of the electrodes in a thin film.

The particular improvements comprising the subject matter of this invention relate to the trommel type'of apparatus and will be fully understood from the following description read with reference to the accompanying drawings of which- 7 Figure 1 is a semi-diagrammatic view in sectional elevation of the whole apparatus;

Figure 2 is a detail sectional elevation of the electrodes;

Figure 3 is a detail sectional elevation of the I right-hand end of the'shaft showing the packing and slipring construction for connecting the shaft to the positive pole of the current; and

. Figure i is an alternative construction of the right-hand end of the shaft.

Referring to Figure l, numeral i designates the horizontal drum or shell which is preferably provided with a jacket 2 through which either heating means or cooling means may be circulated to regulate the temperature within the drum. Numeral 3 designates the rotatable shaft supported by-insulated bearings t and 5 at either end. A plurality of parallel electrodes 6 and 6' are mounted on the shaft. .These may extend in number over the entirelength of the shaft, al-'- though only four are shown in the drawings. The thickness of the electrodes shown in the drawings is purposely disproportionately great compared to the rest of the apparatus in order to illustrate better the construction. The conducting parts. of electrodes 6 are connected to the shaft which is connected to one pole of the circuit. The conducting parts of electrodes 6' are connected by means of brushes I to a conductor 8 which is connected to the other pole. The shaft is rotated by means of motor 9 and gears l0 and H. The shaft projecting through the drum is insulated therefrom. A slipring l2 connected to one pole of the current is disposed around the shaft on the outside of the .drum. Heretofore both connections between the electrodes and the source of current have been placed inside the drum.

The drum is maintained under vacuum by means of a vacuum pump (not shown) connected to pipe [3. Oil or other material to be treated is withdrawn from supply tank l4 through line l5 and may first be introduced into a mixing and agitating tank l6 provided with a. stirring means H. In this tank various materials may be mixed with the oil or the oil may be treated with various agents such as solvents, clay, acid, etc. prior to being introduced into the voltolizing apparatus. From the mixing tank the oil is withdrawn through line l8 by pump l9 and sucked into drum l through'line 2ll. When the feed stock is treated with a reagent, the latter may be introduced into agitator l6 by means of line 45,

settled out and drawn off through lines I8, 46

and valve 41 together with any sludge, etc. The remaining treated oil may then be pumped into the voltolizer I through line 20. The level of the liquid in the drum is maintained somewhat below the center thereof. The product may be drawn off from time to time through line 2| by means of pump 2|a, and all or a portion thereof may be recirculated through the apparatus by means of line 22 and pump 22a.

Referring to Figure 2 which shows the crosssection of the electrodes in detail, numeral 25 designates the rotatable shaft charged through the slipring on the outside of the drum. Numeral 26 designates the positively chargedelectrodes and numeral 2! thenegatively charged electrode. Numeral 28 designates the insulating or dielectric material in which the conducting material 29 is encased. In the preferred form of electrode the conductor is placed between two thin sheets of dielectric material which are sealed charged electrodes-2G makes contact at points A.

with the shaft 25. The conductor of the negatively charged electrodes 28 makes contact at point B'through brush 3!] with the negatively charged cylindrical sheet 3|.

The dielectric material 28 may be any suitable insulating material of suilicient strength to stand :compressed paper, porcelain, earthenware, vulcanized fibre, vulcanized rubber, synthetic rubberssuch as those known in the trade as Thickol, Duprene, polyvinyl acetylene, etc., cellulose derivatives such as cellulose acetate, artificial or synthetic resins such as coumarone resins or those known under the trade-marks Bakelite, Vinylite, Beetleware, Catalin or insulating compositions prepared from natural or artificial resins such as those known under the trade-mark Pertinax. i

The conductor may be of any suitable conducting material, such as metals or alloys or mixtures thereof. As suitable examples may be mentioned aluminum, copper, nickel, iron, silver, mercury or mercury vapor, tantalum, tungsten, vanadium, platinum, tin, lead, molybdenum, zinc, chromium, cobalt, cadmium, etc. Other materials such as carbon, graphite and the like may also be used.

The metal conductor may be in the form of discs, sheets or foil or may be in the form of a mesh screen or corrugated sheet. It may also be deposited or sprayed or sputtered onto the dielectric or metals coated with other metals by electro deposition may be used. The sheet or foil of metal may be afiixed to the dielectric by resins or other adhesive or binding dielectric materials.

If glass is used as the dielectric the electrode may be cast with the metal foil or screen in between two thin sheets of glass. Metal alloys such as those which have substantially the same coefflcient of expansion as glass are particularly useful as conductors when glass is used as the dielectric.

Electrodes constructed in this manner in which the conductor is substantially completely encased in dielectric material are of particular advantage over the usual bare electrodes in that no formation of colloidal particles in the oil occurs. When a bare electrode is used, the high tension current frequently causes small colloidal particles of metal to break off from the electrode, thus contaminating the material undergoing treatment. The present type of electrode avoids this difliculty. Alternate electrodes may be constructed of different conductors and dielectric material, although it is preferable to use the saine materials for each electrode.

Referring to Figure 3, which shows the method of passing the shaft through the drum and connecting the same with the positive pole of the current, numeral 35 designates the rotatable shaft. Numeral 36 designates insulating material between the sha'ftand the shell. Numeral 3'! denotes the shell of the drum. Numeral 38 designates a threaded packing gland containing insulating packing 48 which may be tightened by means of threaded nut. 39 insulated from the shaft by insulation 40. Numeral 41 designates a slipring adapted to slip around the rotating shaft making contact therewith. The slipring is connected to the positive pole of the current by.

52 designates insulation, preferably porcelain,

. and 53 and 54 designate gaskets adapted to make gastight joints. This plug is screwed into a boxlike compartment designated by numeral 6|, on the hollow shaft 51. The left-hand end of the shaft indicated by numeral 62 to which the electrodes are attached need not be hollow.

A cable 58 runs through the hollow shaft 51 and is connected within the compartment 61 to the plug. The gas pressure within compartment 6| is substantially atmospheric so that sparkover across distance B will not occur until the voltage gradient is about 20,000 per inch. A clearance of about one inch will therefore give ample insulation for most voltolization work.

Within the voltolizer the clearance A must be suificiently great to prevent spark-over across the porcelain. This will depend on the voltage and gas pressure within the voltolizer.

Numeral 55 designatesthe wall of the trommel, numeral 56 the bearing, and numeral 60 the source of high potential current. Numeral 59 designates a point rotary contact. On large equipment a slipring would be preferable for this point of contact. A bus wire, not shown, connects the various high tension electrodes to the high tension lead 5|.

It will be understood that various other methods than that illustrated may be used for insulating the shaft from the drum and connecting the shaft to the positive pole of the current. It is of great advantage to have at least one of the electrical leads make contact with' the electrodes outside the drum because it is then possible to adjust the contact points-without having to get inside the drum, as is necessary in the usual trommel type of voltolizing apparatus where contact with the leads is made inside the drum.

It is frequently advantageous to place an inductance coil of proper reactance in parallel across the voltolizer circuit to improve the power factor of the generator. The power factor of voltolization equipment usually runs from 10 to 30% leading, and unless the power factor is corrected to 100%, the losses are high in the generating equipment.

This invention is not limited by any theories of the mechanism of voltolization nor by any details given merely for illustrative purposes, but is limited only in and by the following claims in which it is intended to claim all novelty inherent in the invention.

I claim:

1. In an apparatus for subjecting material to the action of silent electric discharges comprising a. drum adapted to be maintained under vacuum, a rotatable shaft therein, parallel electrodes mounted on said shaft adapted to be alternately connected to opposite poles of a source of alternating current, and means for introducing thereinto and withdrawing therefrom material to be treated, the improvements which comprise dielectric insulation between the shaft and the drum, alternate electrodes connected to the shaft, means for insulating the other electrodes from the shaft, an electrical connection between the shaft by means outside the drum to one pole of the current, an electrical connection between the electrodes insulated from the shaft by means inside the drum to the other pole of the current,

and a. dielectric material encasing each electrode.

each electrode comprises a sheet of metal encased within a dielectric material.

4. Apparatus according to claim 1 in which each electrode comprises a sheet of metal gauze encased within a dielectric material.

5. Apparatus according to claim 1 in which each electrode comprises a thin layer of a metal alloy encased within a dielectric material.

6. Apparatus according to claim 1 in which each electrode comprises a thin layer of a conducting material placed between and in contact with two thin layers of a dielectric material.

GEORGE L. MATHESON. 

